Building floors with ducts



Oct. 8, 1929.

T. E. MURRAY 1,730,472

BUILDING FLOORS WITH DUGTS Filed July 14, 1925 i/LL ZEOMASEM/RRA 4Patented Get. 8, 192% BUILDING FLOOES WITH DUOTS Application filed July14, 1925. SerialNo. 43,442.

In order to fulfill the requirements of wiring some large buildings, thefloors are built with ducts arranged'to take care with reasonableconvenience of the wiring needs of vari- [1.5 ous classes of tenants whomay occupy the buildings, the ducts being such that wires may beinserted as required for telephone orbuzzer or similar connections. Theducts are placed so close together that a desk or table on the floor atany point will be within a few inches of one of the ducts. These arecalled incomplete ducts because generally no floor plates or outlets forthe surface are provided except when needed. Such ducts have a flatbottom surface to permit the introduction of several wires withoutinterference and are-sometimes arched over the top to make a half roundcross-section, and are sometimes rectangular in cross-section. The halfround shape is generally. preferred becauseof the strength of the arch.

Such half round shapes have generally been formed by use of a permanentlining of manufactured fiber for the arch. A concrete waterproof pad isprovided for the edges of the arched fiber to rest on, and concrete iscare fully poured along the edge of the. fiber be-.

fore the finished floor is made up in the usual way. Rectangular ductshave generally been flformed about a rectangular pipe or permanentlining. 7

My invention aims to provide an apparatus and process by which conduitsof half round and similar flat bottomed shapes "can, be

* formed with economy of both material and labor.

The accompanying drawings" illustrateembodiments of the invention.

F 1g. 1 1s a cross-sectlon .of a floor showing 40 conduits at upper andlower levels for outlets above and below respectively;

Fig. 2 is a cross-section of a single conduit used for outlets in bothdirections;

Fig. 3 is a perspective view showing the method of forming the ducts andan outlet to the top surface;

Fig. tis a perspective view of the parts used in forming the lower ductin Fig. 1;

0 5 is a cross-section of a modification.

'drawal. With such comparatively soft rubconcrete in the usual rapidway. The with- Referring to Fig. 1, the floor 1 is of concretesupporting a-tube 19 through whichthe wires pass'downward for connectionto ceiling fiX- tures, The upper ducts 2 may be built without outlets..Their location being known, it is a simple matter to cut an outlet intoa duct from the top surface of the floor. at any dey sired point in itslength and to install a plate a or outlet, box. Or outletopeningsandboxes or .plates can'be installed when the floor is built, for use atpoints whereit is certain such'outlets will be needed. U i 5 'According'to my invention, the ducts are formed by means of a core which,notwithstanding their small cross-section, can be withdrawn endwise soasto leave an unlined duct of desired shape and size. As a core, Ipropose to use a rubber tube of aclosed perimeter, that is, extendingaround the'en} tire contour of the duct, and made of rubber of'a highdegree ofpurity so that after the concrete has been cast around it andhas hardened it can be pulled endwiseand will contract sufficientlyincross-section to free it from the concrete and to permit its withher,the wall of the core has to be of substan- O tial thickness to withstandthe blows and the pressure involved in casting the concrete around it.The tube illustrated has a flat base 8 and an arched top 9. Theconcreteis built up to the level of the bottom of the duct. The cores are thenlaid in the proper locations. It'is only necessary thereafter to pourthe;

drawal ofthe core leaves a duct," the walls of which are constituteddirectly by the surrounding concrete, giving a floor of greatercompression strength than where part ofthe concrete is displacedby alining, 'orgiving a larger duct for the same strength of concrete. Therubber core described leaves a very smoothhard finish on the surroundingcon crete, the smoothness being increased as the concrete is allowed,toharden' longer before the withdrawalof the core. V

Where an outlet is to be provided to the top I gypsum or outside of thecore 8, 9. Tn making'ducts bercore which rests on the of the floorduring the building thereof, a special rubber form,like that in Fig. 8,may be used. Aninner vertical tube 10 has its lower end fitting thearched top 9 of the core and an outer vertical tube 11 fits the innertube with a shoulder at a point above the arch 9. When the concrete iscast, the shape shown in Fig. 2 is produced with a tubular opening 12 atthe upper end of which is a shoulder 13 supporting an aperturedplate 1 1set in the larger opening 15. Two of the cables 16 from the duct 2 areled up through the opening in the plate 14. to the top of the floor,additional cover plates being provided as may be required. To provide anoutlet to the ceiling beneath a hole is cut through slightly largerthan. the pipe 20 which is inserted therein embedded in fine cement,similar material 17 to hold it in lace; the threaded upper endfurnishing a better Through. this pipe wires 18 may be led downward fromthe duct 2.

. Where a bottom outlet is desired, an alternative method is illustratedin Figs. land 4. The ceiling duct 4 is formed about a rubplate 6'. Thelatter is provided with holes at intervalsfrom which pipes 19 aresuspended passing to a point below the ceiling level. After the floor iscast and set, the rubber core is withdrawn leaving the lining 6 at thebottom of the duct permanently in place.

Fig. 3 shows how two cores are brought together to make 'a branchconnection. The 21, 22 is cut off at its end to fit the of, othershapes. in cross-section, the. core will be correspondingly shaped.

,The fiat bottom of the duct Ts formed in the laying ofthe concretebefore the use of the core, lining 6. The essential feature ofthe coretherefore is the shape corresponding with the desired shape of the ductabove the bottom of the latter. For example, assuming an arched shape,we may use. a core as in Fig. 5 consisting only of'a rubber strip 01arched form 9, lying with its edges on the the core then pulled out.

Various-modifications of the invention may bottom 23 and held byshoulders in the concrete or otherwise. The remaining concrete is caston this and allowed to harden and be made by those skilled in the artwithout departing from the invention as defined in the following claims.v

. What I claim is z' 1. The-method of building floors of plasticmaterial with a flat bottomed duct therein which consists in layingtheplastic material to the shape of the flat bottom of the duct, placinga plateon such bottom, placing on such plate a core shaped to correspondwith the desired shape of the duct above the plate,

hold for the imbedding material.

either with or without the bottomcasting theplastic material around thecore, allowing the material to harden and removing the core so as toleave the duct with smooth faces above said plate formed di-' rectly bythe plastic material.

2. A core for forming flat bottomed ducts in floors of plastic material,said core having a flat base adapted to rest on a fiat face of theplastic material and having side portions with lower edges which areheld by said base against spreading, said core being made of rubber ofsufficient thickness to withstand (without internal support) the blowsand pressure involved in casting plastic material around it withoutsubstantial deformation and being of rubber of so high a degree ofpuritythatwhen pulled end-- wise it will contract sufficiently in crosssection' to tree it from the surrounding plastic material and to permitits withdrawal. 3. A core for forming flat bottomed ducts in floors ofplastic material, said core having a fiat base adapted to rest on. aflat "face of the plastic material and an arched of which are held bytop the lower edges said base against spreading, said core being made ofrubber and suflicient thickness to withstand (without'internal support)the blows and pressure involved in casting plastic material around itwithout substantial def ormation and being of rubber of so high a degreof purity that when pulled endwise it will contract sufliciently incross. section In witness whereof, I have hereunto s gned to free itfrom the surrounding plastic material and to permit its withdrawal.

